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The present invention relates to the endoluminal placement of prostheses, particularly within the vascular system for the treatment of cardiovascular disease, such as vascular stenoses, dissections and other tissue separation conditions, aneurysms, and the like. The apparatus and methods, however, are also useful for placement in other body lumens, such as the ureter, urethra, biliary tract, esophageal, bronchial, gastrointestinal tract and the like, for the treatment of other conditions which may benefit from the introduction of a reinforcing or protective structure within the body lumen. The prostheses will be placed endoluminally. As used herein, xe2x80x9cendoluminallyxe2x80x9d will mean placement by percutaneous or cutdown procedures, wherein the prosthesis is transluminally advanced through the body lumen from a remote location to a target site in the lumen. In vascular procedures, the prostheses will typically be introduced xe2x80x9cendovascularlyxe2x80x9d using a catheter over a guidewire under fluoroscopic guidance. The catheters and guidewires may be introduced through conventional access sites to the vascular system, such as through the femoral artery, or brachial and subclavian arteries, for access to the target site.
An endoluminal prosthesis typically comprises at least one radially expansible, usually cylindrical, body segment. By xe2x80x9cradially expansible,xe2x80x9d it is meant that the body segment can be converted from a small diameter configuration (used for endoluminal placement) to a radially expanded, usually cylindrical, configuration which is achieved when the prosthesis is implanted at the desired target site. The prosthesis may be non-resilient, e.g., malleable, thus requiring the application of an internal force to expand it at the target site. Typically, the expansive force can be provided by a balloon catheter, such as an angioplasty balloon for vascular procedures. Alternatively, the prosthesis can be self-expanding. Such self-expanding structures may be provided by a temperature-sensitive superelastic material, such as Nitinol, which naturally assumes a radially expanded condition once an appropriate temperature has been reached. The appropriate temperature can be, for example, a temperature slightly below normal body temperature; if the appropriate temperature is above normal body temperature, some method of heating the structure must be used. Another type of self-expanding structure uses resilient material, such as a stainless steel or superelastic alloy, forming the body segment so that it possesses its desired, radially-expanded diameter when it is unconstrained, e.g., released from radially constraining forces of a sheath. To remain anchored in the body lumen, the prosthesis will remain partially constrained by the lumen. The self-expanding prosthesis can be delivered in its radially constrained configuration, e.g. by placing the prosthesis within a delivery sheath or tube and retracting the sheath at the target site. Such general aspects of construction and delivery modalities are well-known in the art.
The dimensions of a typical endoluminal prosthesis will depend on its intended use and desired anatomy. Typically, the prosthesis will have a length in the range from 0.5 cm to 5 cm, usually being from about 0.8 cm to 5 cm, for vascular occlusive applications. The small (radially collapsed) diameter of cylindrical prostheses will usually be in the range from about 1 mm to 10 mm, more usually being in the range from 1.5 mm to 6 mm for vascular occlusive applications. The expanded diameter will usually be in the range from about 2 mm to 50 mm, preferably being in the range from about 25 mm to 45 mm for aortic applications.
One type of endoluminal prosthesis includes both a stent component and a graft component. These endoluminal prostheses are often called stent grafts. A stent graft is typically introduced using a catheter with both the stent and graft in contracted, reduced-diameter states. Once at the target site, the stent and graft are expanded. After expansion, the catheter is withdrawn from the vessel leaving the stent graft at the target site.
Grafts are used within the body for various reasons, such as to repair damaged or diseased portions of blood vessels such as may be caused by injury, disease, or an aneurysm. It has been found effective to introduce pores into the walls of the graft to provide ingrowth of tissue onto the walls of the graft. With larger diameter grafts, woven graft material is often used. In small and large diameter vessels, porous fluoropolymers, such as ePTFE, have been found useful.
Coil-type stents can be wound about the catheter shaft in torqued compression for deployment. The coil-type stent can be maintained in this torqued compression condition by securing the ends of the coil-type stent in position on a catheter shaft. The ends are released by, for example, pulling on wires once at the target site. See, for example, U.S. Pat. Nos. 5,372,600 and 5,476,505. Alternatively, the endoluminal prosthesis can be maintained in its reduced-diameter condition by a sleeve; the sleeve can be selectively retracted to release the prosthesis. A third approach is the most common. A balloon is used to expand the prosthesis at the target site. The stent is typically extended past its elastic limit so that it remains in its expanded state after the balloon is deflated and removed. One balloon expandable stent is the Palmaz-Schatz stent available from the Cordis Division of Johnson and Johnson. Stents are also available from Medtronic AVE of Santa Rosa, Calif. and Guidant Corporation of Indianapolis, Indiana.
The present invention is directed to an endoprosthesis delivery catheter assembly and method, the assembly being relatively simple in construction, easy and efficient to use and designed so that the functions are intuitive.
A first aspect of the invention is directed to an endoprosthesis delivery catheter assembly comprising a placement catheter having first and second catheter shafts. A handle includes a body and an actuator mounted to the body for movement relative to the body. The proximal portions of the first and second catheter shafts are mounted to the body. At least one of the proximal portions of the first and second catheter shafts are drivenly coupled to the actuator so that movement of the actuator causes rotary and/or axial movement of the first and second catheter shafts relative to one another. The actuator may be mounted to the body for both rotary and axial movement relative to the body so that rotary and axial movement of the actuator causes corresponding relative rotary and axial movement of the first and second catheter shafts.
Another aspect of the invention is directed to a method for placing a coiled endoprosthesis at a target site in a patient including locating a coiled endoprosthesis, mounted to a distal portion of a placement catheter, at a target site within a patient. At least one of the number of turns and the length of the coiled endoprosthesis is selectively changed using a single actuator. The coiled endoprosthesis is then released from the placement catheter.
In a preferred embodiment, the actuator has two degrees of freedom of movement corresponding to the two degrees of freedom of movement, that is axial movement and rotary movement, of the catheter shafts relative to one another. However, the actuator could be constructed so that a single motion, for example rotary motion, could be sufficient to cause both the number of turns and the length of the endoprosthesis to change. The relationship between the amount of rotary movement versus axial movement of the catheter shafts may, with this alternative embodiment, be fixed or adjustable. Such a design may help prevent the user from wrapping the endoprosthesis too tightly or too loosely. Such a design would likely be more complicated than that disclosed in the preferred embodiment.